Mass spectrometry

Question 1

What is mass spectrometry?

Answer 1

Is a technique used to measure the mass of atoms and moles, when we use it for elements, it can help us to determine the relative abundance and presence of isotopes.

Question 2

Mass spectrometers:

Answer 2

-Separates individual isotopes in an element.
- Determines the mass of each isotope relative to carbon -12
- Calculates the relative isotopic abundances of each isotope.

Question 3

How does the mass spectrometer work?

Answer 3

1. Sample is vaporised and then ionised using high energy electrons in the ionisations chamber.
2. Ions are separated and accelerated according to their mass/charge ratio.
   - Higher mass experiences less deflection.
   - Higher charge experiences more deflection.
3. Ions that have a particular m/z ratio are detected by a device that counts the ions that hit it.

Question 4

Mass spectra:

Answer 4

The information from the mass spectrometer is then calibrated into a mass/charge ratio graph for the element’s isotopic ions.

Question 5

Calculate percentage abundance from m/z graph:

Answer 5

%abundance =
(peak height/tot peak heights) x 100